/* $XConsortium: wildmat.c,v 1.2 94/04/13 18:40:59 rws Exp $ */
/*
**
**  Do shell-style pattern matching for ?, \, [], and * characters.
**  Might not be robust in face of malformed patterns; e.g., "foo[a-"
**  could cause a segmentation violation.  It is 8bit clean.
**
**  Written by Rich $alz, mirror!rs, Wed Nov 26 19:03:17 EST 1986.
**  Rich $alz is now <rsalz@bbn.com>.
**  April, 1991:  Replaced mutually-recursive calls with in-line code
**  for the star character.
**
**  Special thanks to Lars Mathiesen <thorinn@diku.dk> for the ABORT code.
**  This can greatly speed up failing wildcard patterns.  For example:
**	pattern: -*-*-*-*-*-*-12-*-*-*-m-*-*-*
**	text 1:	 -adobe-courier-bold-o-normal--12-120-75-75-m-70-iso8859-1
**	text 2:	 -adobe-courier-bold-o-normal--12-120-75-75-X-70-iso8859-1
**  Text 1 matches with 51 calls, while text 2 fails with 54 calls.  Without
**  the ABORT, then it takes 22310 calls to fail.  Ugh.  The following
**  explanation is from Lars:
**  The precondition that must be fulfilled is that DoMatch will consume
**  at least one character in text.  This is true if *p is neither '*' nor
**  '\0'.)  The last return has ABORT instead of FALSE to avoid quadratic
**  behaviour in cases like pattern "*a*b*c*d" with text "abcxxxxx".  With
**  FALSE, each star-loop has to run to the end of the text; with ABORT
**  only the last one does.
**
**  Once the control of one instance of DoMatch enters the star-loop, that
**  instance will return either TRUE or ABORT, and any calling instance
**  will therefore return immediately after (without calling recursively
**  again).  In effect, only one star-loop is ever active.  It would be
**  possible to modify the code to maintain this context explicitly,
**  eliminating all recursive calls at the cost of some complication and
**  loss of clarity (and the ABORT stuff seems to be unclear enough by
**  itself).  I think it would be unwise to try to get this into a
**  released version unless you have a good test data base to try it out
**  on.
*/

#define TRUE			1
#define FALSE			0
#define ABORT			-1


    /* What character marks an inverted character class? */
#define NEGATE_CLASS		'^'
    /* Is "*" a common pattern? */
#define OPTIMIZE_JUST_STAR
    /* Do tar(1) matching rules, which ignore a trailing slash? */
#undef MATCH_TAR_PATTERN


/*
**  Match text and p, return TRUE, FALSE, or ABORT.
*/
static int
DoMatch (text, p)
     register const char *text;
     register const char *p;
{
	register int last;
	register int matched;
	register int reverse;

	for (; *p; text++, p++)
	{
		if (*text == '\0' && *p != '*')
			return ABORT;
		switch (*p)
		{
		case '\\':
			/* Literal match with following character. */
			p++;
			/* FALLTHROUGH */
		default:
			if (*text != *p)
				return FALSE;
			continue;
		case '?':
			/* Match anything. */
			continue;
		case '*':
			while (*++p == '*')
				/* Consecutive stars act just like one. */
				continue;
			if (*p == '\0')
				/* Trailing star matches everything. */
				return TRUE;
			while (*text)
				if ((matched = DoMatch (text++, p)) != FALSE)
					return matched;
			return ABORT;
		case '[':
			reverse = p[1] == NEGATE_CLASS ? TRUE : FALSE;
			if (reverse)
				/* Inverted character class. */
				p++;
			for (last = 0400, matched = FALSE; *++p && *p != ']';
			     last = *p)
				/* This next line requires a good C compiler. */
				if (*p == '-' ? *text <= *++p
				    && *text >= last : *text == *p)
					matched = TRUE;
			if (matched == reverse)
				return FALSE;
			continue;
		}
	}

#ifdef	MATCH_TAR_PATTERN
	if (*text == '/')
		return TRUE;
#endif /* MATCH_TAR_ATTERN */
	return *text == '\0';
}


/*
**  User-level routine.  Returns TRUE or FALSE.
*/
int
wildmat (text, p)
     const char *text;
     const char *p;
{
#ifdef	OPTIMIZE_JUST_STAR
	if (p[0] == '*' && p[1] == '\0')
		return TRUE;
#endif /* OPTIMIZE_JUST_STAR */
	return DoMatch (text, p) == TRUE;
}
